When he lost his job as a Johannesburg gardener a month ago, 25-year-old Sibangani Tsikwe did what millions of men have done before him: seek their fortune deep underground in the gold mines that help to define South Africa.

The decision has probably cost him his life.

Equipped with little more than a head-torch, pick-axe and nerves of steel, Tsikwe and a group of fellow Zimbabweans descended into the bowels of the earth on Sept. 5 via a derelict shaft at Johannesburg's Langlaagte gold mine.

He has not been seen since.

In the annals of South African mining, Langlaagte looms large as the farm where prospectors first stumbled upon gold in 1886, a discovery that would open up the richest veins of gold-bearing rock mankind has discovered.

Since then, the meter-wide seams, or reefs, that stretch for hundreds of kilometers east, west and south across the Witwatersrand Basin have produced more than 2 billion ounces of gold - roughly half of all the bullion ever mined.

In Zulu, Johannesburg is called Egoli, the City of Gold.

Yet history was probably the last thing on Tsikwe's mind as he clung to a length of knotted string tied to a tree stump at the shaft entrance and took his first steps down the 30-degree slope into one of the most dangerous work-places on earth.

Bodies recovered

Scores of illegal miners die each year in the labyrinth of tunnels that stretch beneath the streets of Johannesburg and beyond, although police and the government admit they have no idea of the precise toll.

In most cases after an accident, the miners - mainly illegal migrants from neighboring Zimbabwe, Mozambique, Lesotho or Swaziland - are reluctant to alert authorities for fear of being arrested and deported.

When police and emergency services are called in, mine-rescue teams often deem the risk too great, especially after flooding, fires or rockfalls in 100-year-old tunnels compromised by unauthorized and unregulated digging and blasting.

Tsikwe and his friends had food and water for four days and may well have descended to depths of 4 km and travelled more than 20 km through the tunnels.

When they failed to surface on time, his 24-year-old brother Daroh raised the alarm. Of a 16-strong rescue team of illegal miners that went in the next day, four remain unaccounted for after they ran into clouds of noxious underground smoke.

Early on Tuesday, a joint team of government rescuers and illegal miners brought up one body and a man who is now in critical condition in hospital. Neither was Tsikwe.

"I don't know why he did it," a distraught Daroh, a truck-driver, said as helmeted rescue workers peered into the mouth of the shaft. "It was his first time."

Zama-zama

Known in Zulu as 'zama-zamas', which loosely translates as 'those who try to get something from nothing', illegal miners are now a permanent fixture of the shanties that ring Johannesburg and its satellite towns along the gold reef.

Thousands are thought to be operating at any one time, driven since the turn of the century by gold priced at more than $1,000 an ounce, and the joblessness and economic hardship that prevails across southern Africa.

Although illegal mining is a common problem across many emerging markets, it has become particularly acute in South Africa given the country's mineral riches and the legions of poor people in the region.

In Zimbabwe, unemployment is above 80 percent but on a good trip underground, a zama-zama can recover gold worth 3,000 rand ($210) or more once the ore has been crushed, panned and then 'cleaned' with mercury to remove silt, miners told Reuters.

As a laborer, Tsikwe would have made just 200 rand a day.

"I'll keep going down as long as I have strength in my body, as long as I'm alive," said 61-year-old Justice Ndlovu, a qualified tiler and father of 19 who has been working as a zama-zama for five years.

"What else can I do? I don't trust the government to give me money to live," added the South African.

Shootouts

Besides the frequent accidents, zama-zamas are blamed for outbreaks of violence, including underground shoot-outs between rival gangs, environmental pollution from the use of mercury and links to organized crime through the illicit gold supply chain.

As such, the government takes a dim view of their activities.

Nor is the problem limited to disused shafts, with mining companies such as Gold Fields, Sibanye and Harmony having to use elaborate and onerous security measures such as iris-recognition scanners to prevent illegal miners getting into active mines.

In 2012, then-mining minister Susan Shabangu said the cost to the economy was at least 5 billion rand, mainly in the form of extra security and the need to repair shafts rendered unsafe by zama-zamas.

Standing at Langlaagte mine, Johannesburg police spokesman Kay Makhubela struck a defiant tone, saying anybody coming out of the mine would be arrested for trespass and breach of South Africa's mining laws.

But the reality is the police are powerless to stop the zama-zamas.

Breaking back in

At Langlaagte, where the shaft lies just 400 meters from a police station, the ground is strewn with thousands of discarded batteries from head torches. A half-drum barbecue even stands at the entrance to greet the miners as they return to daylight.

The Department of Mineral Resources, which is responsible for disused mines, says it has blocked up 200 shafts, but with thousands of ventilation and other openings dotted along the reef, it is never going to be able to plug all the holes.

Even blocked shafts seldom stay that way for long, with zama-zamas known to bring in lifting gear and explosives to dislodge concrete slabs or cement plugs, according to the Chamber of Mines, the main industry body.

Taking a different tack, the police and gold companies have teamed up to target those further up the supply chain who spirit the illicit bullion into the local and international mainstream, although so far there have been few convictions.

The Chamber of Mines has even started to argue for partial decriminalization.

"Some artisanal mining, even where unlawful in the current circumstances, has the potential to become beneficial to communities if properly regulated," it said in a report published this year.

But until the economies of the region start providing alternative sources of income for the millions of unemployed, little is likely to change.

"Whenever I'm on leave, I come down here," said Sipho Moyo, a security guard from Zimbabwe who has worked as a zama-zama for seven years. "There's no work in South Africa at the moment so you've got to make a plan."